1. Field of the Invention
The present invention relates to an electric steam iron capable of producing steam from water to smooth down the creases in cloth or the like.
2. Description of the Prior Art
Various types of electric steam irons are currently available in the market. For example, the Japanese Laid-open Pat. Publications No. 60-129095 published in 1985, No. 61-263493 published in 1986, and No. 3-295597 published in 1995, discloses such electric steam irons as reproduced in FIGS. 8 to 10 of the accompanying drawings, respectively.
Referring first to FIG. 8, the prior art steam iron disclosed in the Japanese Laid-open Pat. Publication No. 60-129095 has a vaporizing chamber 3 defined in an iron base plate or soleplate 2 adapted to be heated by a heater 1. Water within a removable tank 4 is supplied dropwise into the vaporizing chamber 3 through a nozzle 5 so that, when the soleplate 2 is heated, drops of water so supplied can be vaporized to produce steam. The nozzle 5 is selectively opened and closed by a valving mechanism 7 adapted to be manipulated by a spray button 6. The prior art steam iron also has a pump unit 8 built therein for supplying an additional amount of water dropwise into the vaporizing chamber 3 to temporarily increase the amount of steam being sprayed to thereby enhance removal of the stubborn creases from the clothing.
The prior art steam iron shown in FIG. 8 has some disadvantages. Namely, since the nozzle 5 and a discharge port of the pump unit 8 both provided in the tank 4 are separate from each other and are fluid-coupled with the vaporizing chamber 3, not only are complicated seals required one for each of the nozzle 5 and the discharge port of the pump unit 8, but it is difficult to avoid a water leakage which would occur from a connection between the vaporizing chamber 3 and each of the nozzle 5 and the discharge port of the pump unit 8.
Also, if the user of the steam iron inadvertently depresses the spray button 6 to open the nozzle after the heater 1 has been electrically energized, but before the vaporizing chamber 3 attains a vaporizing temperature required for the water therein to be vaporized, the water supplied dropwise into the vaporizing chamber 3 egresses as a heated water without being vaporized and, once this occurs, the clothing being ironed may be stained.
Moreover, where the valving mechanism 7 is repeatedly driven up and down at a time during an ironing job, the vaporizing chamber 3 is rapidly cooled down to a temperature lower than the vaporizing temperature at which the water can be vaporized. Even in this case, the water supplied dropwise into the vaporizing chamber 3 egresses as a heated water without being vaporized and, once this occurs, the clothing being ironed may be stained. Furthermore, if the user having completed the ironing job fails to set the spray button 6 in position (i.e., in a depressed position) to close the nozzle 5 while the water remains within the tank 4, the water remaining within the tank 4 will leak into the vaporizing chamber 3, causing the wall defining the vaporizing chamber to be corroded.
The prior art steam iron of a type shown in FIG. 9, i.e., that disclosed in the Japanese Laid-open Patent Publications No. 61-263493, appears to effectively eliminate the foregoing problems inherent in the steam iron shown in FIG. 8. This prior art steam iron shown in FIG. 9 makes use of a thermo-responsive valve assembly 10 including a valve rod and a bimetal element 11 mounted on the soleplate at a location immediately beneath the valve rod and operatively associated with the bimetal element. This thermo-responsive valve assembly 10 is disposed on a guide passage 9 communicating between the tank 4 and the vaporizing chamber 3, so that when the water within the vaporizing chamber 3 is heated to the vaporizing temperature, the bimetal element 11 can be convexed in response to the temperature of the soleplate 2 to lift a valve rod of the thermo-responsive valve 10 to thereby open the guide passage 9. A pump unit 12 employed for a purpose similar to the pump unit 8 employed in the steam iron shown in FIG. 8 is also disposed on the guide passage 9 and includes a normally upwardly biased pumping member 13 which, when driven repeatedly up and down, pumps water from the tank 4 through the guide passage 9 into a cylinder 14 and then discharges into a portion of the guide passage 9 adjacent the vaporizing chamber 3 to thereby supply an increased amount of water into the vaporizing chamber 3 so that the steam being sprayed can be temporarily increased to enhance removal of the stubborn creases from the clothing.
When the pumping member 13 is locked in a depressed position having moved against a biasing force necessary to keep the pumping member 13 at a normally upwardly biased position, the guide passage 9 can be closed to interrupt the supply of water from the tank 4 towards the vaporizing chamber 3. On the other hand, at the normally upwardly biased position of the pumping member 13, the latter is clear from the guide passage 3, allowing the supply of water from the tank 4 towards the vaporizing chamber 3 to effect a standard steam spraying.
According to the prior art steam iron shown in FIG. 9, a water discharge port of the tank 4, a discharge port of the pump 12 and the valve rod of the thermo-responsive valve 10 are required to be disposed at respective positions spaced horizontally from each other, but substantially in level with each other, and this structural requirement increases the distance from an intake port of the guide passage 9 to an outlet port thereof along an upper region of the soleplate 2. The greater the length of the guide passage 9, the lower the response is in which a relatively large time lag occurs in initiating or stopping the spray of steam in response to selective opening or closure of the guide passage 9.
In addition, considering that when the iron is used for actual ironing without the steam spraying function utilized the guide passage 9 is overheated by the heat evolved in the soleplate 2, supply of water into the guide passage 9 in an attempt to spray the steam while the guide passage 9 is overheated results in boiling of water within the guide passage 9 accompanied by cavitation to suffocate the guide passage 9. Once this occurs, a smooth flow of water through the guide passage 9 is hampered to such an extent as to result in the incapability of the steam iron to accomplish a stabilized spraying of steam.
The prior art steam iron shown in FIG. 9 is advantageous in that since the single pumping member 13 has, in addition to the standard steam spraying function of selectively initiating and interrupting a standard steam spraying, an enhanced steam spraying function in which the quantity of steam being sprayed is temporarily increased, the steam iron as a whole can be designed compact in structure. However, this convenient feature often poses a problem in that if when the pump 12 is desired to be operated the pumping member 13 is inadvertently depressed a distance greater than required, spraying of the steam is abruptly halted. If, however, a regulator means is employed for avoiding an excessive depression of the pumping member beyond the required distance, a different problem would occur in that a relatively strong force may be required to depress the pumping member to overcome the force developed by the regulating means, thereby rendering the pumping member to be difficult to handle.
When the steam iron of the structure shown in either FIG. 8 or FIG. 9 is used for actual ironing, the front tip of the soleplate 2 is often utilized to tactically remove creases from, for example, a narrow and/or confined area of the clothing. In any one of the prior art steam irons shown respectively in FIGS. 8 and 9, it is often experienced that the field of view of the user looking down at the creases in the narrow and/or confined clothing area from above during an actual ironing job with the steam iron being moved to and fro is obstructed by the stem of a body of the steam iron adjacent the front tip of the soleplate. This is because the stem of the prior art steam iron is steeply angled relative to the soleplate or the surface to be ironed, as clearly shown in either FIG. 8 or FIG. 9, with the front tip of the soleplate barely protruding outwardly from a lower region of the stem of the steam iron. To avoid this problem associated with the viewability, the Japanese Laid-open Pat. Publications No. 3-295597 discloses the steam iron of a structure shown in FIG. 10.
Referring to FIG. 10, the prior art steam iron shown therein includes a removable water tank 15 of a generally U-shaped configuration as viewed from top. This removable tank 15 has a stem edge where the opposite side wall of the tank body converge and where a water fill port 16 is defined is substantially streamlined rearwardly to reduce the angle .alpha. of inclination of the stem edge relative to the soleplate 2 to thereby permit the user to look down conveniently at the creases in the narrow and/or confined clothing area during the ironing without being substantially obstructed by the stem of the water tank 15.
Since the water fill port 16 is defined in a region of the rearwardly streamlined stem edge, even the prior art steam iron shown in FIG. 10 however has a problem particularly when the tank 15 is removed from the body of the steam iron for refilling water into the tank 15 through the water fill port 16 and is then held with the water fill port 16 laid substantially horizontally, i.e., substantially transverse to the direction of flow of water from a spout. This is because, when water is to be refilled with the water fill port 16 held substantially horizontally, the tank 15 as a whole must be tilted against an ergonomic aspect of tank holding. On the other hand, if the tank 15 removed from the body of the steam iron is held upright with its bottom lying substantially horizontally, the water fill port 16 then tilts relative to the direction of flow of water from the spout or faucet, making it difficult to refill the tank 15.
In addition, when the tank 15 is to be removed from the body of the steam iron then heated to an elevated temperature such as occasionally exercised, for example, when water is to be refilled into the empty tank 15 or when water remaining within the tank 15 is to be removed after the ironing job, or when the refilled tank 15 is to be mounted on the body of the heated steam iron, a covering skirt 17 overhanging the sole plate 2 and heated to an elevated temperature is prone to be touched by the user's hand and, therefore, there is a relatively high possibility that the user may burn his or her hand on a portion of the hot covering skirt 17 adjacent the front tip of the soleplate 2.